


Unseen

by Kuroshitdrabbles



Category: Kuroshitsuji | Black Butler
Genre: A/B/O, Alpha/Beta/Omega Dynamics, Alpha/Omega, M/M, Omegaverse, Power Bottom Ciel, SebaCiel - Freeform, gamma!sebastian, s/d/g, sigma!ciel, subdynamics
Language: English
Status: Completed
Published: 2018-09-16
Updated: 2018-09-19
Packaged: 2019-07-12 22:50:29
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 3,603
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16004936
Author URL: https://archiveofourown.org/users/Kuroshitdrabbles/pseuds/Kuroshitdrabbles
Summary: You can't hide your dynamic. Everyone knows that red is alpha, blue is omega, and yellow is beta.Sebastian and Ciel have purple marks.





	1. Purple

From the time pups are born they have a thin line of faint color around their wrists. With how strong Sebastian was as a baby, his parents truly believed he'd be an alpha like his father. When he was born he was the only pup in his litter to have a light purple mark. In Ciel's little litter of three, his two siblings were born with a blue line and he had a dark purple one. Ciel was a sigma. Most people called him an unruly omega, which made him so _fucking_ mad. He _wasn't_ an omega. Just because about 15 sigmas were born a year didn't mean they could be written off in such a casual fashion. He gave off omega scents, could bare pups, but his heats were unlike that of a true omega.

"Medium iced black coffee."

"I'm sorry, _what_ size?"

Ciel growled. He said medium, he didn't feel like saying grande. The beta quickly averted her eyes and took his order. His sweater rolled up when he went to give her his card, her eyes staring in awe at his mark.

"You-you're a gamma?"

" _No_."

He spat.

"I'm a _sigma_. Not that it matters. Stop asking questions and make my _fucking_ coffee."

She was still mesmerized, looking at him like he was magic or something. He stared daggers at her until she gave him his card again. When he turned to sit down he was ran into by a much bigger man, hot coffee scorched his delicate skin.

"Hey, fucking _watch it_!"

He growled in a high pitch. He was surprised when the, seemingly, alpha man teared up and whined softly.

"I-I'm so fucking _sorry_ I just, I-"

Tears ran down his face freely. Ciel grabbed his arm, _light purple_.

"Oh, for fucks sake."

He huffed a growl and let go of his arm.

"I-I'll pay for your coffee, and I'll buy you a new sweater! I'm really really sorry."

He stuttered out, so nervous to be met with any kind of confrontation.

"It's _fine_."

He grumbled out, face a deep red.

"It's _not_ , I ruined your sweater because I was careless and-"

He started crying again.

"Sit. _Now_."

The stranger nodded and went to sit at his table, fidgeting lightly. He got his coffee and sat across from him.

"What's your name."

"Sebastian."

"Cool. I'm Ciel."

The stranger- _Sebastian's_ eyes flickered to the floor.

"Uh, I'm really sorry for ruining your sweater."

"I'm not here to make you apologize."

"T-then why _are_ you here?"

Ciel lowered his voice

"You're a _gamma_."

Sebastian's eyes widened.

"Oh, uh, yeah."

"I'm not gonna call you weak."

"What are you gonna do?"

God, he's so fucking nervous. Ciel pulled his sleeve up, watching a wide smile spread across Sebastian's face.

"Y-you're a sigma?"

" _Yes_."

Ciel laughed. Maybe it was weird that he made Sebastian sit down with him, but he was so excited, he had never met another subdynamic before.

"Wow, that's amazing! I've never met one before!"

"Me neither!"

They were chirping at each other. Two strangers chirping at one another was a bit unheard of, except in bad fanfiction. This was something completely new, and Ciel was thrilled.

 

 

❤

 

 

 

Six months later Sebastian had given Ciel about a thousand sweaters. The 'alpha' in him wanting to please his boyfriend and bring him tiny gifts as often as he could.

 

"Thank you, Sebastian."

 

 Ciel smiled, gratefully taking a cup of tea that had been prepared for him.

 

  "You're very thoughtful."

 

  Sebastian smiled so wide. He climbed onto the couch and pulled Ciel into his lap, big arms holding him extremely close. The gamma scented him thoroughly, unintentionally getting Ciel scent drunk.

 

  "S-Sebastian..."

 

 His eyes were hooded, lust taking over, lazily scenting him back.

 

 "You're a good boy."

 

 Sebastian teared up

 

 "Y'really think so?"

 

  " _Yes_ , Sebastian."

 

 Sebastian nuzzled Ciel's neck, trying to coax more of his scent out.

 

 "Wanna be even more of a good boy?"

 

 The noiret nodded eagerly.

 

  "Eat me out."

 

 Never afraid to say exactly what he wants. Sebastian didn't waste any time going down on Ciel, purring at how he cried out for more and forcibly gripped his hair. He wasn't in heat but he still produced a small amount of slick. It was basically a concentrated version of his boyfriends scent, he whined against Ciel's entrance for more, he shuddered and gripped Sebastian's hair harder.

 

 "Feels so _good_ , Sebastian, you're so _good_."

 

 He was still clearly controlling this situation, but his submissive role was showing with the way he moaned. He didn't _have_ to ask for more, Sebastian was all to eager to give. The gamma slipped a finger inside his boyfriend, crooking it against his prostate and still licking fat stripe around it, a delicious splash of slick escaped Ciel.

 

 "O- _oh my god_ , Sebastian, jus- _just_ a little more, _hnn_ , I'm s-so close, _fuck_."

 

That made him even more eager, wanting to keep pleasing his little sigma. If not the words, the way Ciel's thighs clamped around his head was proof. He came with a high cry, pulling hard at Sebastian's hair, loosening his grip when he was coming down from the high, pulling harder when Sebastian didn't stop.

 

 " _S-seb-sebastian_!"

 

 He perked his head up at the call, cute smile on his face.

 

 "Mmhmm?"

 

 "Sit down on the couch, sweetest."

 

He wanted to make Ciel cum again but obediently did as he was told.

 

"Gonna give you a treat for being so good."

 

Sebastian gasped lightly when Ciel swallowed the entirety of his length in one go.

 

"Th- _thank you_ , Ciel."

 

The slate haired boy hummed a ' _mhm_ ' around him, sending vibrations up his spine. It was impressive that Ciel could take all 8" without a lot of struggle. Since gammas were evolved from submissive alphas, their tendencies were mostly like that of an omega, but dynamically and physically they were more like alphas.

 

"L-love you _so much_ , Ciel."

 

Big stupid love bug. That's all Sebastian was, just a giant teddy bear who nuzzled Ciel every single day, mustered up the courage to growl at people who looked his way, smothered his sigma in cuddles after endless cuddles.

 

"L-look so pr-pretty, Ciel."

 

He chirped, his dick being surrounded in amazing warmth. He wouldn't knot right now, he wasn't rutting. 

 

"C- _can_ _I_...?"

 

He asked, too worked up to finish his question. Ciel pulled off for a moment.

 

"You ask that every time, and every time I say yes."

 

He plunged back down, letting Sebastian's dick hit the back of his throat. Sebastian shot his cum in Ciel's mouth, the smaller boy swallowing it all down promptly. He pet Ciel's hair lovingly. The boy climbed back onto the couch, laying on his back and silently inviting Sebastian to cuddle.

 

"Love you."

 

Sebastian purred, peppering kisses all over Ciel's face and neck. The sigma purred as well, crooning softly.

 

"I love you too, Sebastian."

 

The noiret's phone dinged.

 

_Rut in 14 hours!_

 

He whined.

 

"Hmm? What's wrong?"

 

"I'm gonna rut soon."

 

Ciel smiled

 

"Maybe we can spend our cycles together. I can feel my heat coming on."

 

Sebastian smiled so widely.

 

"You mean it? You really want to?"

 

" _Yeah_ , Sebastian."

 

The gamma looked at the floor momentarily.

 

"Th-think we'll, y'know... _mate_?"

 

Ciel scratched Sebastian's scalp lightly.

 

"I'd really like that."

 

Sebastian purred and chirped so loudly, nuzzling Ciel's neck and kissing him over and over. He never thought he'd find a mate, being a gamma and all, but here he was. When he calmed down he wrapped his big arms around Ciel and rested his head on the sigmas chest.

 

"I love you."

 

He said sleepily.

 

"I love you, too."

 


	2. Unusual Bonding

_Rut in 3 hours!_

 

Sebastian went about the house gathering blankets, pillows, and some clothing, putting it all into a pile for Ciel to make a nest out of. The younger man grumbled all throughout the day, angrily making a nest, ripping some things to shreds out of pure frustration. He didn't dare tear apart all the stuffed animals Sebastian got him, though, he wasn't a monster. And as embarrassing as it was, sometimes when he's tired he slips into a less dominant role, nuzzling and scenting all the stuffed creatures, maybe even being so tired that he thinks they're his pups. Ciel sat in his nest, demanding Sebastian come lay down next to him to assess the size. He shook his head again, redoing the nest for the fourth time. 

 

"C-ciel, it looked really good before."

 

"Not good _enough_." 

 

Sebastian accepted defeat and went into the kitchen, grabbing a few supplies like water and chips. He also went about tidying up their house before they were completely lost to their cycles. Gammas ruts were more like omegas heats, becoming a bit nonverbal and whiny for attention. Sigmas heats were a lot like alphas ruts, a lot of frustration and tension needing to be released by sex, but still having the need to make a nest. 

  
"Gamma, come."

He demanded, tone not unlike how a human would talk to their dog. Sebastian scrambled with all the supplies he had grabbed and did as he was told, shuffling his big body into their room, seeing the nest that Ciel was still picking at. He had to get every detail right.

"Ciel, y-you're adjusting a _sock_."

"It's not _facing_ the _right way_."

Sebastian crawled into the nest and draped his body over Ciel's shoulders, kissing his neck lovingly.

"You're a _dork_."

"And _you're_ heavy."

Sebastian huffed a laugh and lifted his body slightly so Ciel could still feel strong but also not crush his boyfriend.

"F-fifteen minutes, Ciel."

Ciel stopped nit picking his nest.

"Do you wanna cuddle for a little bit?"

Sebastian nodded and pulled Ciel down, stuffing his face into his neck and wrapping his big arms around him.

"M'love you."

Ciel sighed and pet Sebastian's head.

"I love you too, Sebastian. How many times do I have to say it?"

"Over n over n over!"

Sebastian smiled when his boyfriend chuckled lightly.

"Is that right?"

"Yep!"

Ciel sratched his head, liking how Sebastian leaned into the touches.

"Th-think we'll have pups?"

Ciel shook his head

"I'm on birth control. Maybe next time."

Sebastian nodded and playfully nipped at Ciel's neck.

"H-hey! Love you!!!"

"I _know_ , Sebastian. You big sap."

Didn't stop Sebastian from saying it over and over everyday. As time passed more and more whines emitted from Sebastian's throat, pushing his face further into Ciel's neck with each sudden burst of arousal. Ciel knew what was happening to him, but he wanted to cuddle for just a little longer. Five minutes passed and then-

"C-ciel, can I k-knot you?"

Ciel purred against his face, nuzzling his strong jawline and pushed him onto his back. He straddled him in no time, grinding down onto Sebastian's very prominent erection.

"Oh, baby. Coulda asked from the start."

Sebastian was struggling to keep himself together, the promise to be buried inside Ciel at such a vulnerable time drove him absolutely _crazy_. Ciel took his time removing his clothing while Sebastian took his off in mere seconds. Eager boy. He could see that Ciel was dripping slick, how badly he just wanted his boyfriend to take mercy on him and sink down onto his dick. The slate haired boy captured Sebastian's lips in a kiss and finally, finally sat on the noiret's pulsating cock. Sebastian whined at how good it felt, how long he's wanted this (like 15 minutes but hey, he's needy). He always wanted Ciel to be happy, satisfied. What if he was a bad mate? A bad _father_? A bad _boyfriend_? Would Ciel ever _want_ to marry him? All these thoughts made him tear up while Ciel rode him. The sigma noticed and started producing more of his scent for Sebastian to sniff up, calmimg him slightly.

"Seb, what's wrong?"

"L-love you."

Ciel sighed, goddamn he was such a big baby. He leaned down to Sebastian's neck and bit down _hard_ at his mating glad. He was his now. Nobody else's, his. The gamma chirped with newfound happiness, he had been _claimed_. He was even happier when Ciel bared his neck for Sebastian, a small act of submission. He quickly bit down and licked over the wound in a small apology. Ciel straightened his back again to pick up his pace once more, Sebastian couldn't stop smiling. Mouth pulled at each corner to make a big goofy grin. Ciel really did love him, it was just difficult to be as sappy as his boyfriend, it wasn't in his dynamic. Sigmas smell, look, have tendencies like omegas but were very _very_ stubborn and dominant. That's why Ciel couldn't gush over Sebastian the same way Sebastian did to him. It was hard but he really did try. He bounced with vigour, sharp nails emerging and digging their way into Sebastian's chest, nothing lethal just tiny claws scratching a bit. Not that Sebastian would mind either way. Ciel could slap him in the face and he'd _relish_ in the attention. He was a bit of a maniac for the small boy. Speaking of small, he's so _tiny_ , how the hell was he taking all 10" of Sebastian's dick? Was he just empty? Is that how he did it? So many questions, so little time. Contrary to most peoples belief, gammas could take knots as well. They kind of _had_ to be able to, considering that their whole dynamic was derived from submissive alphas. So if by some weird chance Ciel _did_ have a knot, Sebastian would be on it instantaneously. Not like he hasn't thought about it. Their first session was coming to a close, as Ciel started losing a lot of his finesse. It was so _easy_ for him to find an angle for Sebastian's big dick to rub _perfectly_ against his g-spot. Honestly, Sebastian could probably drink the slick pouring out of Ciel. It was just so good, Sebastian knew exactly how to please him, even if it was just laying down and letting Ciel be dominant. He loved feeling powerful, even if his dynamic was just 1 tier above the most " _weak_ " class, he wanted to be on top of the world. It wasn't hard to feel that way with Sebastian.

" _Se-seb-sebastian_!"

Sebastian couldn't really speak, gammas went a bit nonverbal during ruts. Not as bad as omegas did but it still proved to be a hassle. Ciel slammed down one last time and spurted all over Sebastian's chest, it didn't take long for Sebastian's knot to expand and for him to cum inside Ciel, who purred at the feeling. Sebastian wanted to pull his small boyfriend down to cuddle, but since Ciel was knotted in this position he'd have to settle with him leaning down and kissing him lazily. When his knot went down Ciel shakily pulled himseld off and laid next to his boyfriend, allowing himself to be the little spoon for a bit.

"Knot me like this next time. So we can cuddle afterwards, I know you'll want to."

Sebastian smiled against his mates neck. Ciel was very displeased when Sebastian left for a moment, but he came back with a little stuffed dog.

"Oh, Sebastian. Did you get that for me?"

He nodded and gingerly gave him the offering.

"I love him. I love him so much that I think I'll name him Sebastian."

The noiret purred at the suggestion. When they fell asleep it wasn't for very long, as two hours later Sebastian would whine and work his cock back into Ciel again. But in the moment it was Sebastian the dog, Ciel, and regular ole Sebastian. That was enough.


	3. Aftermath

Ciel woke up to his sweet gamma rubbing his face against his cheek.

"M-morning!"

Ciel rolled onto his back where he was attacked with kisses. 

"Well, good morning."

It had been a week since their cycles, and Ciel felt like he could finally breathe now that he could think of one thing other than ' _claim_ '. Sebastian was a lot better, too. He was still a big overemotional _idiot_ , but that was to be expected at all times. He hugged Ciel like he was a little stuffed animal which pissed him off sometimes, but in the end he knew it was just the gammas way of showing affection.

"Do you feel better today, love?"

"Y-yep! Feel like I can actually sleep!"

Ciel kissed his cheek

"That's my boy. Wanna go watch TV or something? It's so hot in here."

Sebastian nodded and lifted his body up and crawled out of the nest. He threw on a pair of boxers and a big sweatshirt, Ciel chose to wear the same, except he wore one of Sebastian's. When they got on the couch Sebastian was surprised when Ciel chose to lay on top of him, rather than the other way around.

"I-I know you hate when I say this but y-you look really cute with my sweatshirt on!'

Ciel didn't tense up, he just chuckled against Sebastian's collarbone.

"Thank you, handsome."

"Y-you're not upset?"

Ciel looked up and smiled.

"No, you're my mate. Anyone else who calls me cute can get their throats slit, though."

Sebastian purred and chirped with happiness.

"Y-you mean that?"

"Yes, Sebastian. You're the only person who can call me cute. Promise."

Sebastian had that big stupid smile again. His hands were so huge on Ciels face, but he didn't mind when he got to kiss him.

"Wait!"

Sebastian called.

"Huh?"

"Y'gotta pinky promise!"

It took Ciel a moment to stop laughing, his boyfriend was such a dork. But nonetheless he pinky promised.

"That good?"

"Yep! You're cute!"

Ciel covered his face in kisses

"You're cuter!"

Sebastian was basically always blushing.

"See? Adorable."

Sebastian hugged him so tight, some people would swat at his arms to get him to stop. But Ciel found it endearing. It wasn't a challenge with Sebastian, he never made him question his dynamic. Never made him uncomfortable. Never called him an unruly omega. No, Sebastian just loved him. Loved him like it was his drive.

"D-did you mean it? A few days ago, a-about pups?"

Ciel ran his fingers through Sebastian's hair and sighed before speaking

"I think that if we can handle having a litter then _yes_ , we can try for pups next year."

Sebastian chirped with excitement. Fucking gammas, what a mess.

"They-They'll be so _cute_ , Ciel!! Can you imagine?"

"I can imagine, yes. I think you'll make the best dad, the best hus-"

Wait. Fuck.

"We should get married."

" _R-really‽_ "

Sebastian sat up so fast, Ciel was nearly unseated.

"If we're starting a family, I think it's a good idea."

Sebastian was so happy

"W-we gotta tell everyone! I gotta-"

"Start with your brothers, they'll want to hear."

Siblings always tended to have a unique bond. Sebastian had two brothers and one sister. Two alphas ; William and Claude, one omega ; Grell. Ciel had an alpha sister, Elizabeth. Unfortunately his brother who's name was Ciel passed, he used his name in memory of him. It took forever to get through all the siblings, Lizzie and Grell cried, but other than that everything was well. Sebastian loved his siblings, he'd fight with them often when they were kids, but since they lived further apart they became closer, emotionally. Ciel loved Lizzie, but she was a _lot_. He truly couldn't handle her for long amounts of time. Sebastian was so excited in that moment, he was getting _married_ , he was gonna have a _family_. These were his dreams for a long time. Gammas were so needy, they loved being with their mates. Sebastian was the happiest boy.

"What do you think? Halloween wedding?"

Sebastian kissed Ciel's cheek.

"Don't care! J-jus wanna be with you!"

"We're gonna be together forever now! I swear!"

Sebastian was wriggling with excitement, but Ciel got him to lay down once more, cuddling into his chest.

"Oh, Ciel! I-I'm so happy!"

"That's good! I only ever want you to be happy, my boy!"

"M'always gonna _be_ happy!"

They scented each other, becoming scent drunk and crooning at each other.

"You're the best, Ciel."

No stuttering.

"Thank you, Sebastian. I think you're the best as well."

Ciel poked his nose

"You know my favorite part about you?"

Sebastian hummed a soft ' _hmm_?'

"You never demean me. You have never written me off as a stubborn omega and you never treat me as such. You make me comfortable with my dynamic."

Sebastian took a deep breath.

"I-I really like how you'll let me be th-the little spoon without implying that I-I'm weak."

"You're _not_. You're just needy, and I'm _always_ happy to make you comfortable."

Sebastian nuzzled him further.

"I love you."

Again, no stuttering.

"I love you too, Sebastian."

Ciel pet his gamma, scratching his scalp lightly, giving him tiny kisses on his forehead. All the things that made him purr. The sigma purred as well, always so content in Sebastian's presence. He only gave love to the world, and sometimes it didn't give any back, but he never gave up. He went to a coffee shop for a drink and cried in front of his future mate. Called his brother to talk about how he met another subdynamic. Gave Ciel everything he had and in return had gotten the love of his life. All the ups and downs led him to _this_ moment, them, talking about marriage and pups.

"M'wanna be with you forever."

"We're gonna be, sweetest. Gonna have lotsa pups till we die."

Sebastian laughed a tiny bit, his fiancée was funny, nice, and reassuring.

"Pinky promise?"

"Pinky mother fucking _swear_."

**Notes for the Chapter:**

> And so ends the mini-fic with a/b/o subdynamics! I'll def write more in the future

**Author's Note:**

> Send me stuff on Tumblr @Kuroshitdrabbles


End file.
